Root cause for 100 % disk utilization

[Former Member]

Hi All,

Whenever in one of the dailog instance disk utilization is showing 100% sap system is getting very slow,what is the root cause for 100% utilization .At that moment of time when I checked the CPU usage it showed 98% CPU idle. server is on Windows NT and around 13GB of RAM is always free.

We have only one drive in the apps server.Can this be the cause of 100% disk utilization?

Waiting for ur frequent responses.

Regards,

Prashant

[Former Member]

As in your scenario you have only one disk on which all IO operations takes place.

These operations are at OS level, Application level and DB level.

When a user interacts with SAP it has to go through all these layers to complete the transaction imagining more users on the system IO operations will hit high rates and Disk usage will be more.

I would say you can have additional disks on which app can be hosted.

Regards

Vivek

[Former Member]

Thanks a lot, I will discuss this with the hardaware vendor.

Regards,

Prashant

[Former Member]

Hi,

I have answered similar questions :

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as described above, one thing that cause 100% disk utilization is that writer processes (and read process too) is concentrated only on a single disk (equivalent to single volume group or single logical volume).

we can imagine that a large number of user hitting the single disk (where datafiles exist) on the same time with a huge transaction load.

if we can manage writable datafiles in several locations (equivalent to several volume groups or several logical volumes) where several datafiles exist, writer processes (and read process too) will be distributed to that several locations, so that each location (each disk, each VG or each LV) utilization may not reach 100%.

so it is important to design writable datafiles in multiple location in different disks to prevent 100% disk utilization.

one thing should be remember is to consult with hardware and storage vendor if there is any possibilities bottleneck or I/O issue on your hardware or storage.

hope it help you.

rgds,

Alfonsus Guritno